LINQ——语言级集成查询入门指南(1)

SELECT c.CompanyName, c.ContactName, c.City
FROM Customers c
WHERE c.City != ‘Berlin‘
ORDER BY c.ContactName

var customerNotInBerlin =
   from c in GetCustomers()
   where c.City != "Berlin"
   orderby c.ContactName
   select c;

using System;
using System.Collections.Generic;
using System.Linq;

namespace LINQIntro
{
   class Customer
   {
      public string CustomerName { get; set; }
      public string ContactName { get; set; }
      public string City { get; set; }
      public override string ToString()
      {
         return this.CustomerName + ", " +
            this.ContactName + ", " + this.City;
      }
   }

   class Program
   {
      static void Main(string[] args)
      {
         Program.ShowCustomers();
      }

      public static void ShowCustomers()
      {
         //使用对象初始化程序建立一列customer
         List customers = new List {
            new Customer { CustomerName = "Alfreds Futterkiste",
               ContactName = "Maria Anders", City = "Berlin"},
            new Customer { CustomerName =
               "Ana Trujillo Emparedados y helados",
               ContactName = "Ana Trujillo",
               City = "México D.F."},
            new Customer { CustomerName =
               "Antonio Moreno Taquería",
               ContactName = "Antonio Moreno",
               City = "México D.F."},
            new Customer { CustomerName = "Around the Horn",
               ContactName = "Thomas Hardy",
               City = "London"},
            new Customer { CustomerName = "Berglunds snabbk?p",
               ContactName = "Christina Berglund",
               City = "Lule?"}};

          //查询customer列，指定显示字段
            var customer =
            from c in customers
            where c.City != "Berlin"
            orderby c.ContactName
            select c;

         //在终端显示选择的记录
         foreach (var row in customer)
         {
            Console.WriteLine(row);
         }
         Console.ReadLine();
      }
   }
}

using System;
using System.Collections.Generic;
using System.Linq;

namespace LINQIntro
{
   class Program
   {
      static void Main(string[] args)
      {
         Program.ShowFiles();
      }

      public static void ShowFiles()
      {
         //指定特定目录
         System.IO.DirectoryInfo dirInfo = new
            System.IO.DirectoryInfo(
            "C:\\Program Files\\Microsoft Visual Studio 9.0");

         //找出目录中的文件并选中它
         var directoryList =
            from f in dirInfo.GetFiles("*.*",
              System.IO.SearchOption.AllDirectories)
            where f.Name.StartsWith("re")
            select f;

         //在终端显示选中的记录
         foreach (var row in directoryList)
         {
            Console.WriteLine(row);
         }
         Console.ReadLine();
      }
   }
}

using System;
using System.Collections.Generic;
using System.Linq;

namespace LINQIntro
{
   class Program
   {
      static void Main(string[] args)
      {
         Program.ShowProcesses();
      }

      public static void ShowProcesses()
      {
         //选择进程列表并计划输出
         var processes = from p in
            System.Diagnostics.Process.GetProcesses()
               orderby p.ProcessName
               select new {
                  p.ProcessName, p.Id, p.WorkingSet64,
                  p.Threads, p.HandleCount };

         //在终端显示选择的记录
         foreach (var row in directoryList)
         {
            Console.WriteLine(row);
         }
         Console.ReadLine();
      }
   }
}

using System;
using System.Collections.Generic;
using System.Linq;

namespace LINQIntro
{
   class Program
   {
      static void Main(string[] args)
      {
         Program.ShowEventLog();
      }

      public static void ShowEventLog()
      {
         //加入应用程序事件日志
         System.Diagnostics.EventLog myLog =
            new System.Diagnostics.EventLog();
         myLog.Log = "Application";

         //使用terminated为关键字查询错误记录，你可能想要调整EventLogEntryType和
        //消息以适应你本地的事件日志，注意自定义对象是如何形成的。
         var logEntries =
            from System.Diagnostics.EventLogEntry e in
               myLog.Entries
            where e.EntryType ==
               System.Diagnostics.EventLogEntryType.Error &&
               e.Message.Contains("terminated")
            select new {
               e.Source, e.InstanceId, e.Message,
               e.TimeGenerated };

         //显示选择的记录
         foreach (var row in logEntries)
         {
            Console.WriteLine(row);
         }
         Console.ReadLine();
      }
   }